Basically, a new polyploid plant species has had more than one separate origin in Scotland. And we still don’t know how that works.*
Polyploidy—the heritable condition of possessing more than two complete sets of chromosomes—has always been something of a mystery, and this new find both illuminate it and suggests we should pay more attention to it:
Polyploidy is the heritable condition of possessing more than two complete sets of chromosomes. Polyploids are common among plants, as well as among certain groups of fish and amphibians. For instance, some salamanders, frogs, and leeches are polyploids. Many of these polyploid organisms are fit and well-adapted to their environments. …
Well, from ScienceDaily:
Dr Vallejo-Marin added: “It is impossible to say whether Mimulus peregrinus evolved first in the south or in the north of Scotland, but our discovery of a very young species of this kind has allowed us to study evolution as it happens. We only know of a handful of other plant species as young as Mimulus peregrinus and so in this respect it is like looking at the big bang in the first milliseconds of its occurrence.
“The process of evolution it has followed is particularly interesting and adds complexity to our conception of the tree of life. Instead of branching out as it grows, Mimulus peregrinus is an example of how some branches can come back together again and spawn new species that are in part the combination of their ancestors.”
Which makes it kind of difficult to track evolution. Yes it happens, but not like the Darwin lobby rams into textbooks.
Here’s the abstract:
Whole genome duplication (polyploidisation) is a mechanism of “instantaneous” species formation that has played a major role in the evolutionary history of plants. Much of what we know about the early evolution of polyploids is based upon studies of a handful of recently formed species. A new polyploid hybrid (allopolyploid) species Mimulus peregrinus, formed within the last 140 years, was recently discovered on the Scottish mainland and corroborated by chromosome counts. Here, using targeted, high-depth sequencing of 1200 genic regions, we confirm the parental origins of this new species from M. x robertsii, a sterile triploid hybrid between the two introduced species M. guttatus and M. luteus that are naturalised and widespread in the United Kingdom. We also report a new population of M. peregrinus on the Orkney Islands and demonstrate that populations on the Scottish mainland and Orkney Islands arose independently via genome duplication from local populations of M. x robertsii. Our data raise the possibility that some alleles are already being lost in the evolving M. peregrinus genomes. The recent origins of a new species of the ecological model genus Mimulus via allopolyploidisation provide a powerful opportunity to explore the early stages of hybridisation and genome duplication in naturally evolved lineages. (paywall) – Mario Vallejo-Marín, Richard J. A. Buggs, Arielle M. Cooley, Joshua R. Puzey. Speciation by genome duplication: Repeated origins and genomic composition of the recently formed allopolyploid speciesMimulus peregrinus. Evolution, 2015; DOI: 10.1111/evo.12678
* See Douglas E. Soltis, Richard J. A. Buggs, Jeff J. Doyle and Pamela S. Soltis (2010) What we still don’t know about polyploidy Taxon 59: 1387-1403:
ABSTRACT During the past decade there has been a tremendous resurgence of interest in polyploidy that has in large part been stimulated by the development of increasingly powerful genetic and genomic tools. The result has been numerous new insights into the genomic and genetic consequences of polyploidy. The plethora of new discoveries has dramatically reshaped traditional views and concomitantly revealed that polyploidy is a highly dynamic and ubiquitous process. These recent advances in our understanding of polyploidy have stimulated numerous reviews, most focused on the various genetic, epigenetic, and genomic consequences of polyploid evolution. Whereas genetic and genomic attributes of polyploidization have received considerable attention, other crucial areas of polyploid evolution have received much less (e.g., ecology, pollination biology, physiology). The focus of this paper is not to review again recent discoveries, but to emphasize what we do not yet know about polyploidy, which despite all that has been learned about genome doubling is still an enormous amount. Our list is not meant to be comprehensive, but includes a range of topics that we have placed in several general categories, including mode of formation, ecological and physiological consequences, and genomic rules. Questions include: What is (are) the most frequent mechanism(s) of polyploidization? What factors promote/facilitate polyploidization? What factors favor autopolyploid vs. allopolyploid formation? Do multiple origins result in lineages with differing evolutionary trajectories and/or cryptic species? Our major goals are to stimulate discussion and promote further research. Download.
Follow UD News at Twitter!
Search Uncommon Descent for similar topics, under the Donate button.